iw.js

/*
 * Copyright (c) 2015 Christopher M. Baker
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 */

var child_process = require('child_process');

/**
 * The **iw** command is used to control nl80211 radios.
 *
 * @static
 * @category iw
 *
 */
var iw = module.exports = {
  exec: child_process.exec,
  scan: scan
};

/**
 * Returns a truthy if the network has an ssid; falsy otherwise.
 *
 * @private
 * @static
 * @category iw
 * @param {object} network The scanned network object.
 * @returns {string} The ssid.
 *
 */
function has_ssid(network) {
  return network.ssid;
}

/**
 * Returns a truthy if the network has any key; falsy otherwise.
 *
 * @private
 * @static
 * @category iw
 * @param {object} network The scanned network object.
 * @returns {boolean} True if any key.
 *
 */
function has_keys(network) {
  return Object.keys(network).length !== 0;
}



/**
 * A comparison function to sort networks ordered by signal strength.
 *
 * @private
 * @static
 * @category iw
 * @param {object} a A scanned network object.
 * @param {object} b Another scanned network object.
 * @returns {number} The comparison value.
 *
 */
function by_signal(a, b) {
  return b.signal - a.signal;
}

/**
 * Parses a scanned wireless network cell.
 *
 * @private
 * @static
 * @category iw
 * @param {string} cell The section of stdout for the cell.
 * @returns {object} The scanned network object.
 *
 */
function parse_cell(cell) {
  var parsed = { };
  var match;

  if ((match = cell.match(/BSS ([0-9A-Fa-f:-]{17})\(on/))) {
    parsed.address = match[1].toLowerCase();
  }

  if ((match = cell.match(/freq: ([0-9]+)/))) {
    parsed.frequency = parseInt(match[1], 10);
  }

  if ((match = cell.match(/signal: (-?[0-9.]+) dBm/))) {
    parsed.signal = parseFloat(match[1]);
  }

  if ((match = cell.match(/last seen: ([0-9]+) ms ago/))) {
    parsed.lastSeenMs = parseInt(match[1], 10);
  }

  if ((match = cell.match(/SSID: \\x00/))) {
    delete parsed.ssid;
  }
  else if ((match = cell.match(/SSID: ([^\n]*)/))) {
    parsed.ssid = match[1];
  }

  if ((match = cell.match(/DS Parameter set: channel ([0-9]+)/))) {
    parsed.channel = parseInt(match[1], 10);
  }
  else if ((match = cell.match(/\* primary channel: ([0-9]+)/))) {
    parsed.channel = parseInt(match[1], 10);
  }

  if ((match = cell.match(/RSN:[\s*]+Version: 1/))) {
    parsed.security = 'wpa2';
  }
  else if ((match = cell.match(/WPA:[\s*]+Version: 1/))) {
    parsed.security = 'wpa';
  }
  else if ((match = cell.match(/capability: ESS Privacy/))) {
    parsed.security = 'wep';
  }
  else if ((match = cell.match(/capability: ESS/))) {
    parsed.security = 'open';
  }
  return parsed;
}

/**
 * Parses all scanned wireless network cells.
 *
 * @private
 * @static
 * @category iw
 * @param {function} callback The callback function.
 *
 */
function parse_scan(show_hidden, callback) {
  return function(error, stdout, stderr) {
    if (error) callback(error);
    else
      if (show_hidden) {
        callback(error, stdout
        .split(/(^|\n)(?=BSS )/)
        .map(parse_cell)
        .filter(has_keys)
        .sort(by_signal));
    } else {
        callback(error, stdout
        .split(/(^|\n)(?=BSS )/)
        .map(parse_cell)
        .filter(has_ssid)
        .sort(by_signal));
    }
  };
}

/**
 * The **iw scan** command is used to scan for wireless networks
 * visible to a wireless interface. For convenience, the networks are
 * sorted by signal strength.
 *
 * @static
 * @category iw
 * @param {string} interface The wireless network interface.
 * @param {function} callback The callback function.
 */
function scan(options, callback) {
  var interface, show_hidden
  if (typeof options === 'string') {
    var interface = options;
    var show_hidden = false;
  } else {
    var interface = options.iface;
    var show_hidden = options.show_hidden || false;
  }

  this.exec('iw dev ' + interface + ' scan', parse_scan(show_hidden, callback));
}